GB1147462A - Sewing machine - Google Patents

Abstract

1,147,462. Sewing machines. GENERAL AUTOMATED MACHINERY CORP. 16 May, 1966 [28 May, 1965], No. 21601/66. Heading D1G. A sewing machine is provided with electrically-operable three-way valves for pneumatically controlling apparatus adapted, on the advance of a workpiece, to start the sewing machine, to lower the presser foot aand to sever the 'thread chain extending to the previouslysewn workplace, and on completion of the workpiece to raise the presser foot and to stop the sewing machine. The sewing machine is driven by an electric motor 16 via a clutch and brake unit 15 so arranged that supply of compressed air to a pipe 21 serves to engage a disc 139, rigid with the driven shaft 130, with a brake ring 140, while supply of compressed air to a pipe 20 serves to engage disc 139 with a disc 142 on the motor shaft 150. A pipe 113, connected to the casing of unit 15, is vented to the atmosphere through an aperture 171. Cylinders 9 and 189 are connected to a pipe 23, supply of compressed air to which thereby serves respectively to raise the presser foot and to lower thread-cutting means to a thread-engaging position. A solenoid valve 35 has a normallyclosed port 19a connected to a compressed air supply pipe 19, a normally-open port 59b connected to a pipe 59, and a normally-open port 60a connected by a pipe 60 to pipe 113. A solenoid valve 38 has a normally-closed port 91 connected to pipe 113, a normally-open port 57a connected to pipe 59, and a normally-open port 92 connected to pipes 21 and 23. A solenoid valve 39 has a normally-closed port 89 connected to pipe 59 and to a pipe 24, a normally-open port 58a connected to pipe 113, and a normally-open port 90 connected to pipe 20, to a needle-cooling nozzle 13, and to a pipe 22. Pipe 24 is connected to a resilient diaphragm 48 operatively coupled to a normally-open microswitch 32, and ends in a control unit 10 comprising a pivoted bar (11) adapted, when engaged by a work piece, to close pipe 24. Pipe 22 is connected to normally-open ports 178 and 179 of solenoid valves 172 and 173 respectively. Valve 172 has a normallyclosed port 174 connected to pipe 23, and a normally-open 'port 176 connected to the thread-cutting means raising end of cylinder 189. Valve 173 has a normally-closed port 175 vented to the atmosphere and a normallyopen port 177 connected to the presser foot lowering end of cylinder 9. The arrangement is such that manual closure of a switch 30 serves to energise the solenoid of valve 35 via lines 34, 36 to close port 60a and to interconnect ports 19a, 59a. Air thereby passes via the ports 57a, 92 of valve 38 to pipe 21 for applying the brake, and through pipe 23 to cylinders 9 and 189 for raising the presser foot and lowering the thread-cutting means. A work piece then presented to the stitching point engages bar (11) of unit 10 to close pipe 24, whereby full pressure is applied to diaphragm 48 for closing switch 32. The solenoids of valves 38 and 39 are thereby energised via lines 44, 187, 188 and one pole of a treadle-operated switch 185. Ports 57a and 58a are thereby closed, while port 91 is connected to port 92 and port 89 is connected to port 90. Air thus passes to pipe 20 for starting the machine, needle-cooling air flows from nozzle 13, and air passes to pipe 22, and hence through ports 178, 176 to cylinder 189 for raising the treadcutting means to sever the thread chain, and also through ports 179, 177 to cylinder 9 for lowering the presser foot. Disengagement of bar (11) on completion of the work piece allows switch 32 to open for de-energising valves 38 and 39. If the treadle is actuated to change the polarity of switch 185 while the machine is operating, valves 38 and 39 are deenergised, while valves 172 and 173 are energised via lines 186, 187' to close ports 178, 179 and to connect port 174 to port 176 and port 175 to port 177. The machine thereby stops and the presser foot is raised, cylinder 9 being exhausted via port 175, but cylinder 189 is not actuated to lower the thread-cutting means, since both ends of 'the cylinder are connected to the pressurised pipe 23.